Ubuntu Server 18.04.5 upgrade to 20.04 fails
Solution 1:
UPD:
Looks like you trying to install wrong udev version. For bionic download and install http://mirrors.kernel.org/ubuntu/pool/main/s/systemd/udev_237-3ubuntu10.50_amd64.deb
You can try to comment out line /lib/systemd/system/systemd-udevd.service:26 till upgrade will be finished
sudo sed -i '/ExecReload/s/.*/#\0/g' /lib/systemd/system/systemd-udevd.service
sudo systemctl daemon-reload
Than try to upgrade once again
sudo do-release-upgrade